The objective of this project is to study sperm abnormality and the action mechanism of male sterility induced by gossypol. The progress of using this drug as a male sterilant has been hampered by some of its toxic side effects and the lack of understanding of the action mechanism of induced male sterility. Dr. Gregory Lee and Dr. H. V. Malling have made an earlier observation that out of over 20 enzymes investigated gossypol inhibited lactate dehydrogenase-X (a sperm specific enzyme). They also observed that there are certain breakdown products of gossypol which had a much stronger inhibition of LDH-X. It is uncertain if gossypol itself, the breakdown products, or both are exhibiting inhibitory effects by the same or different mechanisms. During treatment of animals and humans with gossypol the development of the male germinal cells disintegrate. When the treatment terminates most animals and humans regain their fertility indicating that germinal stem cells were intact. The crucial question is therefore: is the inhibition of LDH-X by gossypol the major course of male sterility or are the correlation of the two biological effects only incidental.